The invention relates to a filling pipe for a fuel tank having an enlarged housing for holding a closure cap, the housing contains an insert having a collar for selectively holding the outlet pipe of a fuel nozzle. The housing is, as a rule, a deep-drawn part made of sheet metal which adjoins the upper end of the filling pipe, forms an enlargement and then, as far as the outer end, is a cylinder of larger diameter. The insert serves, inter alia, for guiding the inner end of the inserted fuel nozzle. Different inserts are used depending in each case on the type of fuel, design variant and country of destination of the vehicle.
Housings, which are known from practice and into which the insert is inserted and is secured by flanging or crimping (a rolling method reducing the diameter) the housing, form the prior art. The upper part of the insert protrudes out of the housing and forms the thread for the closure cap. The insert has therefore to be connected tightly to the housing. Since the tightness cannot, however, be ensured in this manner, a seal has additionally to be inserted between the insert and housing before they are connected. This is labor-consuming and unreliable, requires complicated tool variants, a subsequent tightness check and, on top of everything else, it can no longer be detached. As a result, it cannot be interchanged when making repairs or if there are changes in the law.
A further disadvantage is that the connection has to take place mechanically and therefore already at the pre-installation stage. The differentiation between the different variants in the manufacturing process so far upstream is a very great disadvantage for the logistics.
It is therefore an object of the invention to improve the known filling pipes qualitatively with regard to production, logistical costs and interchangeability.
According to the invention, the foregoing object is achieved wherein the housing has, on its inner circumference, a number of inwardly directed threaded segments and at least one vertical indentation, in that furthermore the upper part of the housing has segmented threaded parts for screwing the closure cap into, and its lower part is contracted to the diameter of the filling pipe and contains an insert which has, on its outer circumference, a number of outwardly directed threaded segments and two outwardly directed lugs, the former together with the inwardly directed threaded segments of the housing holding the insert in the longitudinal direction, and the lugs together with the at least one indentation forming a safeguard against twisting.
The starting point is thus first of all to form the thread for the closure cap, which thread is generally an internal thread, on the insert. As a result, the seal between the housing and insert is spared. The threaded segments, lugs and indentations can be manufactured in an extremely simple manner and nevertheless with good accuracy.
The threaded segments permit the insert to be introduced into the interior of the housing without being twisted and, as a consequence, provide a bayonet-type connection to the housing. The lugs are used for safeguarding against twisting as soon as the insert, on being twisted, has reached its end position. It is thus ensured that the connection is not released, for example due to vibrations. In spite of this, the insert, or one of the many country-specific variants of an insert, can be inserted very simply and without effort in the vehicle even not until the later final installation, and can be interchanged at a later point.
In a preferred refinement, one of the two lugs forms a catch which can be pressed in elastically, and the other forms a stop, which lugs interact in each case with the at least one vertical indentation. When the end position is reached, rotation first of all takes place over the yielding catch until it snaps into place and at the same time the stop is also reached. Since the indentations extend in the longitudinal direction and only their circumferential position has to be precisely determined, they can be formed very easily at the same time as the housing, which consists of sheet metal, is deep-drawn. It is even better if two mutually opposite indentations are provided, of which one interacts with the catch and the other interacts with the stop.
In an advantageous development, the lower edge of the insert is of conical design on the outside and bears in a sealing manner against the lower part of the housing, which part is contracted to the diameter of the filling pipe. As a result, just one row of threaded segments is needed and a good fit of the insert is obtained.
Owing to the invention, the formation of the housing with an internal thread for holding a closure cap at its upper end is also possible by said housing having at said end segmented turns of an internal thread for holding a closure cap, the central angle of the distance between the turns being larger than the central angle of the outwardly directed threaded segments of the insert.
In a further refinement of the filling pipe according to the invention, the insert can have connecting means for an installation tool. If it is then also still a single part and consists of plastic the installation is particularly rapid and simple.